Toss the squash with 2 teaspoons of the oil, 1/4 teaspoon of the salt, cumin, nutmeg and cinnamon. Spread the cubes out on half of the baking sheet pan. Toss the sliced onion with 1 teaspoon of the oil and spread it out on the other end of the sheet pan. Place in the oven for 10 minutes, toss and roast another 5 minutes, or until the squash is fork-tender and the onions cooked through. Push the onions over to clear a space in the center of the pan; place the walnuts there in a single layer and return to the oven for 1-2 minutes, until the walnuts are very lightly browned and aromatic.

While the vegetables roast, cook the pasta. Bring a large pot of lightly salted water to a boil; add the pasta and cook 5 minutes. Add the kale and cook another 5 minutes, or until the pasta is al dente. Scoop out and reserve 1/4 cup of the water and drain.